people have already expressed problems with the 'size 1-2-3-4-5,etc' system of screw sizes
compound that with being in another country and i can definitely imagine that you would have problems
i assume the screws you need are for holding the finished case together?
well whatever they are for i would just estimate
go into the italian hardware store knowing what the screws are goign to be used for in your project and do your best to find one that looks suitable
anyways screws (even in italy im sure!) are pretty cheap so you can go back if they are an unsuitable size
if that doesnt work then i suggest using your drill to bore rigatoni into the thing, that usually works
